This invention relates to devices for purifying water in an aquarium, and more particularly to an improved ultraviolet lamp assembly for such device.
A known ultraviolet lamp assembly used in devices for purifying water in aquarium, as shown in FIG. 1, comprises a tubular housing 1 with open ends, two plugs 3 removably secured to the open ends of the housing 1 against fluid pressure and an ultraviolet lamp 2 retained by the plugs 3 in the housing 1 and cooperating therewith to provide an annular fluid flow channel 13 for fluid to be irradiated. An inlet port 11 is formed in an end portion of the housing 1 for connection to a source of fluid under pressure to be irradiated and is directly communicating with the fluid flow channel 13. An outlet port 12 is formed in another end portion of the housing 1 and is also directly communicating with the fluid flow channel 13 for discharging irradiated fluid.
It is found that in such known devices during operation of the lamp, calcium and other colloidal matter tends to coat the lamp envelope or other transparent medium separating the fluid from the lamp, thus building up a scale or other contamination which reduces the intensity of the ultraviolet rays and therefore reduces the effectiveness of the lamp in destroying the microorganisms. Moreover, the water or fluid to be irradiated flowing directly from inlet port 11 to outlet port 12 is too short in distance and too soon in time spending to be fully sterilized. To this end, the inventor has attempted to make an improved ultraviolet lamp assembly to overcome the drawbacks of a known ultraviolet lamp assembly.